Quick Answer
The United States spans six main time zones across its states and territories: Eastern, Central, Mountain, Pacific, Alaska, and Hawaii-Aleutian, with a difference of up to five hours between the earliest and latest of the contiguous states, and up to six hours when including Hawaii. Most of the continental US also observes daylight saving time, shifting clocks forward in spring and back in autumn.
The Six US Time Zones
| Time Zone | Standard Time Offset From UTC | Example States |
|---|---|---|
| Eastern Time | UTC minus 5 hours | New York, Florida, Georgia |
| Central Time | UTC minus 6 hours | Texas, Illinois, Louisiana |
| Mountain Time | UTC minus 7 hours | Colorado, Arizona, Utah |
| Pacific Time | UTC minus 8 hours | California, Washington, Oregon |
| Alaska Time | UTC minus 9 hours | Alaska |
| Hawaii-Aleutian Time | UTC minus 10 hours | Hawaii |
Time Difference Compared With the UK
During UK winter, Eastern Time is typically five hours behind the UK, Central Time six hours behind, Mountain Time seven hours behind, and Pacific Time eight hours behind. These gaps can shift by an hour for a brief period around spring and autumn clock changes, since the US and UK do not always change their clocks on exactly the same date.
Daylight Saving Time in the US
Most of the continental United States observes daylight saving time, moving clocks forward one hour in spring and back one hour in autumn. Arizona is a notable exception, generally not observing daylight saving time in most of the state, which means its time difference from neighbouring Mountain Time zone states shifts depending on the time of year.
Why Some States Sit in Unexpected Time Zones
Time zone boundaries in the US do not follow state lines perfectly, and some larger states span more than one zone. This is largely due to historical decisions balancing daylight hours with population centres and economic ties to neighbouring regions, rather than a strict geographic rule, which is why checking the specific city or area matters more than assuming based on the state alone.
Coordinating Calls and Travel Across US Time Zones
- Always confirm which specific time zone a US city or contact is in, since assuming based on the state can be misleading for larger states
- When booking domestic US flights, double check whether times shown are in the departure or arrival airport’s local time zone
- For scheduling calls spanning both US coasts, remember the three hour gap between Eastern and Pacific Time, which is often the largest practical scheduling challenge within the continental US
- Factor in Arizona’s lack of daylight saving time if scheduling anything involving the state during the summer months
US Territories and Additional Time Zones
Beyond the six main zones covering the fifty states, several US territories, including Puerto Rico and Guam, follow their own additional time zones, which is worth checking separately if travel or business involves these regions specifically.
Frequently Asked Questions
How many time zones does the US have in total?
Six main zones across the fifty states, Eastern, Central, Mountain, Pacific, Alaska, and Hawaii-Aleutian, plus additional zones covering various US territories.
Does every US state observe daylight saving time?
No, Arizona is the main exception among the states, generally not observing daylight saving time for most of its territory.
What is the time difference between New York and Los Angeles?
Three hours, since New York follows Eastern Time and Los Angeles follows Pacific Time.
Why is Arizona’s time zone confusing?
Because it generally does not observe daylight saving time, its time difference from neighbouring Mountain Time zone states changes depending on the time of year.
How far behind the UK is Pacific Time?
Typically eight hours behind during UK winter, though this can shift briefly around spring and autumn clock changes.